Question

在我的应用程序中，我从拾取器中获取图像，然后尝试在单独的视图中显示它。

在我的MainViewController.m中我有

-(void)imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary*)info
{
[picker dismissViewControllerAnimated:YES completion:^ {

    self.image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setObject:UIImagePNGRepresentation(self.image) forKey:@"imageKey"];
    [defaults synchronize];

    PublishViewController *publish = [self.storyboard instantiateViewControllerWithIdentifier:@"Publish"];
    [self presentViewController:publish animated:YES completion:nil];
}];
}

然后我尝试在PublishViewController.m中检索图像

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
NSData *imageData = [[NSUserDefaults standardUserDefaults] objectForKey:@"imageKey"];
UIImage *userImage = [UIImage imageWithData:imageData];
self.image = [[UIImageView alloc] initWithImage:userImage];
}

虽然图像没有显示。有什么理由吗？

Answer 1

也许在-viewDidLoad中的完成块之前调用PublishViewController.m中的dismissViewControllerAnimated:completion:并且NSData尚未保存在NSUserDefaults中。
您可以将代码加载到self.image中的PublishViewController.m中加载-ViewDidAppear 现在我说我同意评论者认为NSUserDefaults可能不是存储图像数据的最佳位置。

Answer 2

您最好使用NSUserDefaults来保存图片，而不是使用NSFileManager。

在MainViewController.m的pickerController委托方法中，放置以下代码 -

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    [self dismissViewControllerAnimated:YES completion:nil];

    UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
    NSData *imageData = UIImageJPEGRepresentation(image, 1);

    //This code will save your image so you can retrieve it anywhere else within the app.
    NSFileManager *manager = [NSFileManager defaultManager];
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDirectory = [paths objectAtIndex:0];
    NSString *fullPath = [documentDirectory stringByAppendingPathComponent:@"yourImageName.jpg"];
    [manager createFileAtPath:fullPath contents:imageData attributes:nil];
}

您可以将图像名称保存为您喜欢的任何内容

然后在viewDidLoad PublishViewController.m的{{1}}内放置此代码以检索图片 -

-(void)viewDidLoad{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:@"yourImageName.jpg"];
    UIImage *retrievedImage = [UIImage imageWithContentsOfFile:fullPath];
    self.yourImageView.image = retrievedImage;
}

在此UIImageView PublishViewController的视图控制器上放置yourImageView，我已将其称为{{1}}。

这适用于您正在寻找的内容，希望它有所帮助。

谢谢，吉姆。

UIImage无法从NSUserDefaults检索

2 个答案: